Drip coffee maker for use within a microwave oven

ABSTRACT

The invention includes a brewing apparatus which makes coffee, tea or the like by the drip method within a microwave oven. The brewing apparatus includes a reservoir for retaining a quantity of water for heating which is positioned on a carafe for receiving a quantity of brewed coffee, tea or the like therein. A basket supported on the reservoir retains coffee grounds, tea leave or the like while permitting brewed material to pass therethrough. A pump tube is attached to the reservoir and extends into the cavity formed thereby to a position below the water line. The reservoir is formed such that the application of microwave energy heats the water within the cavity, causing a pressure increase. The pressure forces liquid through the inlet of the pump tube. The pump tube direct the heated water through the outlet onto the coffee grounds, tea leaves or the like within the basket. The brewed material then passes from the basket into the carafe. The reservoir may be removed from the top surface of the carafe and the coffee, tea or the like served therefrom.

This is a division of application Ser. No. 07/310,447, now U.S. Pat. No.4,999,466, filed Feb. 13, 1989.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a coffee brewing apparatus which makescoffee by the drip method. Particularly, the invention is for brewingdrip coffee within a microwave oven. The brewing apparatus retains aquantity of water during heating by the microwave energy, substantiallycontinuously pumps the heated water onto coffee grounds within a basketand deposits the brewed coffee into a carafe.

BACKGROUND OF THE INVENTION

Previous apparatus to make "microwave coffee" either use the percolationmethod (U.S. Pat. No. 4,642,443), or control the deposit of heated wateronto the coffee grounds by a temperature sensitive valve (U.S. Pat. No.4,104,957, No. 4,381,696 and No. 4,132,239.) These valve controlledmicrowave coffee makers are adapted to open at a predeterminedtemperature when heated by the water retained in a reservoir. Uponopening of the valve, the entire quantity of water retained within thereservoir is deposited onto the coffee grounds.

SUMMARY OF THE INVENTION

A preferred embodiment of the present invention includes a drip stylecoffee brewing apparatus which operates within a microwave oven. Thecoffee making apparatus is preferably positioned on a carafe forming abase or support. A water reservoir forms a lid for the carafe andretains a quantity of water within a cavity for heating by the microwaveenergy. A pump tube is provided on the reservoir and seals the cavityfrom ambient air. The pump tube inlet extends into the reservoir to aposition below the water line, closely adjacent the bottom surface ofthe cavity. The pump tube outlet is positioned above a basket retainingcoffee grounds. The basket is supported on the reservoir above theopening into the carafe. The basket includes a perforated bottom surfaceadapted to retain coffee grounds while permitting brewed coffee to passinto the carafe. The basket may also include a perforated lid todistribute the flow of water deposited thereon. The basket is made ofmetal in order to shield the coffee grounds from the microwave energyduring the brewing cycle.

The above described apparatus brews coffee according to the followingsteps. The reservoir is filled with the quantity of water intended to bebrewed into coffee. A corresponding amount of coffee grounds is placedwithin the basket and the basket is positioned on the reservoir. Thepump tube is placed into the cavity and seals the water in thereservoir. The reservoir is placed on top of the carafe and supportedthereby. The carafe and reservoir are inserted into the cavity of themicrowave oven and exposed to the microwave energy therein. Themicrowave energy acting on the water within the sealed cavity of thereservoir causes the fluid to heat and increases the pressure within thecavity. The pressure increase is such that water is cyclically pumpedfrom the cavity through the pump tube. The pump tube directs the waterthrough its outlet onto the lid of the coffee basket. The heated waterflows into the basket and onto the coffee grounds. The heated waterpartially dissolves the coffee grounds to brew coffee. The brewed coffeepasses through the perforated bottom surface of the basket and iscollected within the carafe. The carafe is removed from the microwaveoven upon transfer of substantially all the water from the cavity. Thereservoir is removed from the top of the carafe and the coffee isserved. Other features of the invention will become apparent bydescribing a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 shows the invention retained within the cavity of a typicalmicrowave oven.

FIG. 2 is a side cross-sectional view of the preferred embodiment of theinvention.

FIG. 3 is a top cross-sectional view thereof.

FIG. 4 is an exploded view thereof.

FIG. 4A is an exploded view of an alternate embodiment thereof.

FIG. 5 is an alternate embodiment of the spreader plate portion of theinvention.

FIG. 6 is a second alternate embodiment of the spreader plate portion ofthe invention.

FIG. 7 is a cross-sectional view of the spreader plate of FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

In the figures where like numerals indicate like elements there is shownthe coffee brewing apparatus 10 of the type preferred by the presentinvention. FIG. 1 illustrates the apparatus positioned within the cavityof a microwave oven 12. The microwave oven 12 is contemplated to be ofany type available on the market. However, a microwave oven of at least600 watts is preferred for conveniently brewing approximately 6 cups ofcoffee, i.e., 30-36 ounces (65 cubic inches) of water. Lower wattageunits may drastically effect the time to sufficiently heat the water forbrewing, and thus extend the brewing cycle.

As particularly illustrated in FIGS. 2, 3 and 4, the apparatus 10generally comprises a reservoir portion 14 which is adapted to bepositioned on and supported by a vessel such as a carafe 16. Thereservoir 14, as shown, is supported on the upper rim 18 of the carafe16 with portions extending into the carafe 16. The carafe 16 isgenerally contemplated to be made of a microwave pervious or transparentmaterial. Additionally, it is preferred that the carafe 16 betranslucent or transparent so that the brewed coffee may be viewedthrough the side walls thereof.

The carafe 16 includes a handle 19 which is attached to the side wallsthereof. The handle 19 may be attached to the carafe 16 in any mannerdesired. However, if the handle 19 is attached by use of a metal band orincludes metal portions, the method of attachment must contemplate thefact that adjacent metal surfaces may cause arcing within the oven whenexposed to microwave energy. The top portion of the handle 19 iscontemplated to be attached to the carafe 16 adjacent to the upper rim18 thereof. As illustrated, a cavity 21 is provided adjacent the bottomsurface of the reservoir 14 so as to permit the reservoir 14 to beseated on the rim 18 while remaining level. The cavity 21 providesclearance for the attachment of the handle 19 to the rim 18.

The reservoir 14 preferably includes a tubular or donut shaped bodyportion 20 defining an enclosed tubular cavity 22. A central opening orpassageway 24 is provided through the middle of the body 20. Attached tothe body 20 are handles 26 positioned at any convenient location on theside walls thereof for lifting the reservoir 14 off of the carafe 16when the brewed coffee is to be poured. The handles 26 may either bemolded as part of the body 20 or may be attached by a solvent orultrasonic welding to the side walls.

The reservoir portion 14 may be formed by any convenient method asdesired. These methods include blow molding of the entire structure orthe joinder of an upper and lower portion by means of ultrasonicwelding. As shown in FIG. 2, the reservoir 14 is formed from an upperand lower portion having a projecting rim 23 around the entire peripheryof the body 20. The rim 23 is formed from typical vibration weldingjoints having a male and female portion. The structures of these jointsare not contemplated to be a portion of the present invention other thanforming the reservoir body 20 and sealing the side walls of cavity 22.

Attached to the bottom surface of body 20 is a shelf 28 generally havinga U-shape. The shelf 28 is adapted to receive a coffee basket 30 withinthe open end thereof and support the basket 30 from the bottom surfaceof the body 20. The coffee basket 30 as shown includes an outwardlyprojecting rim 32 which rests on inwardly projecting surfaces 34 ofshelf 28. The coffee basket 30 is slid onto surface 34 such that thebasket 30 is positioned substantially in alignment with opening 24.Spring fingers 78 which are cantilevered, flexible portions within thewalls of the shelf 28 are provided adjacent surface 34 at the ends ofthe U-shape. The spring fingers 78 may include inwardly projecting tabs80 so as to retain the basket 30 and lid 36 within the shelf 28 duringmovement of the reservoir 14.

The reservoir 14 and its constituent parts are preferably made of amicrowave transparent material, such as polycarbonate. Other microwavetransparent materials, such as polypropylene, may also be used. However,the reservoir 14 of the present apparatus 10 is contemplated to bepositioned close to the magnetron outlet of the microwave oven 12.Therefore, the reservoir material will be subjected to a high rate ofmicrowave energy, since less scattering will have taken place upon firstintroduction into the oven cavity. This positioning of the reservoir 14will heat the water at a faster rate, reducing brewing time. However,the more durable material under these conditions is the polycarbonateand such is preferred.

The basket 30 is preferably made of metal, such as stainless steel, orother microwave impermeable material. It is desired that the basket orother structure shield the coffee grounds from microwave energy duringbrewing to prevent burning thereof. The basket 30 preferably includes alid 36 which rests on the inside or top surface of the rim 32. The lid36 may also be microwave impermeable, but is preferably made of amicrowave transparent material. If the lid 36 is made of metal, cautionmust be taken since contact or positioning in close proximity of themetal basket rim 32 with other metal surfaces may cause the materials toarc when microwave energy is applied. Arcing may cause the surfaces ofthe basket 30 to deteriorate and/or create heat, causing deformation ofthe shelf 28 such that it will no longer support the basket 30. Wherethe lid 36 is made of a microwave permeable material, the water withinthe reservoir 14 will act as a microwave shield for the coffee groundswithin the basket 30. This is due to the fact that microwave energy actson water, vegetable and mineral in that order. The mass of the water inthe reservoir 16 will absorb the microwaves directed toward the top ofthe basket 30 during heating until the water has been transferredthrough the brewing cycle.

On the top of body 20 is provided an opening 38. Inserted within theopening is pump tube 40. Opening 38 includes a projecting rim 42. Pumptube 40 includes a surface 44 which is intended to mate with rim 42. Agasket 46 is positioned on surface 44 and is intended to engage theinternal surface of the rim 42 so as to seal the cavity 22 and retainthe pump tube 40 within the opening 38 during brewing.

Pump tube 40 includes an inlet tube 48 which extends through the opening38 and into cavity 22. The bore of tube 48 is preferably 3/8 inch indiameter. This dimension may vary, however, depending on the desiredflow rate to be passed through the pump tube 40. Inlet tube 48communicates with an outlet tube 54 through passageway 56. Outlet tube54 is positioned directly above the opening 24 through the center of thebody portion 20. The conduit formed by the pump tube 40 via the inlettube 48, passageway 56 and outlet tube 54 is not required to be sealedwith respect to the ambient air. However, it is preferred that the pumptube 40 direct the fluid from the inlet 48 to the outlet 54 withoutspillage.

Tube 48 preferably extends to a position closely adjacent the internalbottom surface 50 of the body 20. Within the cavity 22, is provided awell 52 which extends slightly below the bottom surface 50 such that theinlet 48 for pump tube 40 maybe located at a level below bottom surface50. Thus the inlet 48 will be below the water line until substantiallyall of the fluid is removed from the reservoir 14. The bottom surface 50may also be drafted so as to angle towards the well 52 within the cavity22.

The outlet 54 of pump tube 48 is preferably positioned above a spreaderplate 58 within opening 24. Fluid flow passing through the outlet 54will be deposited onto the spreader 58 and its flow will be restrictedthereby prior to being deposited onto the lid 36 of the basket 30. Asshown in FIG. 3, the spreader plate 58 includes a series of circularopenings 60 to restrict the flow to the lid 36. Alternate embodiments ofthe spreader are illustrated in FIGS. 5, 6 and 7. FIG. 5 generally showsa spreader 58' having triangular shaped slots 60' extending radiallyabout the center. This spreader embodiment 58' of FIG. 5 is generallycontemplated for use in making tea or the like by replacing the coffeegrounds in the basket 30 with tea leaves. The greater restriction offlow formed by the slots 60' in spreader plate 58' is sufficient toproperly brew the tea which has a preferred flow pattern and flow ratedifferent from that for brewing coffee. The spreader embodiment 58"shown in FIGS. 6 and 7 includes a single opening 60" having a generallytapered surface 62 extending downwardly towards the coffee basket 30. Itis contemplated that any of these spreader plate embodiments could beprovided as interchangeable inserts which may be inserted into theopening 24 in the reservoir body 20 and replaced as desired. As shown,the spreader plates are formed as part of the body portion 20.

The lid 36 may also include means for restricting the water flow to thecoffee grounds within the basket 30. The surface of the lid 36 ispreferably the same as that on the bottom surface of the basket 30.These surfaces include a series of generally rectangular slots or lancedlouvers which are arranged in a uniform pattern. These slots areapproximately 1/4×1/8 inches in dimension and form openings at thebottom of approximately 0.026 inches in height. Slots of this size andform permit the fluid to pass through the surface without the coffeegrounds or the like also passing therethrough. This type surface isgenerally contemplated to meet the requirements of the coffee industryfor retaining water on the grounds within the basket for properly brewedcoffee. However, other surface configurations or a basket using a filteris also contemplated by the present invention.

FIG. 4A shows an alternate embodiment of the pump tube 40'. Pump tube40' is attached to the body 20 by means of a locking wedge 64 on theinside surface of the opening 38 and projecting tabs 66 on the outsideof surface 44'. Additionally, an O-ring 68 is provided between aninwardly projecting shoulder 70 and the top portion of the pump tube40'. The shoulder 70 forms a seat for the O-ring 68 upon positioning ofthe pump tube 40' within the opening 38. The pump tube 40' is insertedinto the opening 38 with the projecting tabs 66 moving through slots orbreaks 72 in the shoulder 70. The tabs 66 when positioned below thebottom surface of the shoulder 70 are rotated, along with the outlet end54 of the pump tube 40', so as to move under the locking wedge 64. Thisrotation and locking action places the O-ring seal 68 in compressionagainst the shoulder 70, the rim 42 and the pump tube 40' and seals thecavity 22. Release of the pump tube 48' from this locked position iscaused by depression of the pump tube 40' against the resilient biasingof the O-ring 68. Tabs 66 are rotated underneath the locking wedge 64and released through slot 72.

The operation of the apparatus 10 is generally contemplated to be asfollows. First, the pump tube 40 is removed from the opening 38 andwater is poured into cavity 22. The pump tube 40 is replaced within theopening 38 with the gasket 46 (or O-ring 68) forming a seal betweensurface 44 and the projecting rim 42. The inlet 48 of the pump tube 40extends below the water line within the cavity 22 with its endpositioned closely adjacent the bottom surface 50 of the reservoir 14and preferably within well 52. Coffee grounds are placed within thebasket 30 and the lid 38 is placed over the grounds. The basket 30 isthen slid onto the shelf 34, retained by spring fingers 78 and therebysupported below the body 20. The reservoir 14 is then placed on top ofthe carafe 16 such that the basket 30 is positioned within the interiorof the carafe 16 and the reservoir 14 rests on the upper rim 18. Theapparatus 10 is then placed into the cavity of the microwave oven 12with the oven being set for operation.

Upon exposure of the microwave energy to the apparatus 10, the waterwithin the cavity 22 is heated. The heating of the water increases thepressure within the cavity 22. This increase in pressure causes water tobe forced upwardly through the inlet tube 48 and through passageway 56,and to be expelled from outlet tube 54. Outlet tube 54 directs theheated water onto the spreader plate 58. The water passes through theopenings 60 in the spreader 58, onto the lid 36 and then onto the coffeegrounds within the basket 30. As the coffee grounds are exposed to theheated water, the grounds partially dissolve and coffee is brewed. Thebrewed coffee then passes through the bottom of the basket 30 and intothe carafe 16. It is preferred that the carafe 16 be sized such that thelevel of the brewed coffee fills only to a position below the bottomsurface of the coffee basket 30.

The change in pressure caused by the heating of the water within thesealed cavity of the reservoir body 20 is contemplated to fluctuatecyclically over the heating cycle due to the disbursement of waterthrough the outlet tube 54 and the associated reduction in water masswithin the cavity 22. However, the movement of the water through thepump tube 40 is contemplated to be sufficient to provide a substantiallyconstant flow onto the coffee grounds and sufficient to pump nearly allof the water from the cavity 22.

It is generally contemplated that 5 to 6 cups of coffee, that is 30 to36 ounces of water, can be brewed in 5-6 minutes by a microwave ovenhaving 1,000 watts. The donut or tubular shaped reservoir body 20 isdesigned to increase the surface area of exposure of the microwaveenergy so as to maximize the heating of the water. Upon transfer of allwater from the reservoir 14, through the brewing cycle and into thecarafe 16 the apparatus 10 is removed from the oven 12. The reservoir 14is taken off of the rim 18 of the carafe 16 and the coffee served.Handles 26 are provided on the reservoir 14, since the heated water maycause the reservoir material to heat during brewing. However, since thematerial of the reservoir 14 and the remaining portions thereof arepreferably contemplated to be microwave permeable, the microwave energydoes not substantially heat the material being used.

It is also contemplated that the apparatus of the present invention maybe pressurized such that the brewing process would be capable ofpreparing Espresso. Such would be accomplished by sealing the outlettube 54 with respect to passageway 24 within body portion 20.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specifications, as indicating the scope of theinvention.

I claim:
 1. An apparatus for use within a microwave oven, comprising: areservoir defining a closed chamber for retaining a quantity of waterfor heating by microwave energy, a carafe for receiving a quantity ofheated water, pump tube means removably attached to the reservoir, thepump tube means having an inlet and an outlet end, the inlet endextending into the reservoir to a position adjacent the bottom surfaceof the chamber, the attachment of the pump tube means to the reservoirsealing the chamber from ambient air pressure, a basket having aperforated bottom surface supported below the outlet end of the pumptube means, whereby the microwave energy of the oven is directed ontothe water retained in the reservoir, heating the water, the heating ofthe water in the closed, sealed chamber of the reservoir means over timeincreasing vapor pressure within the reservoir, the pressure increaseforcing the heated water through the inlet end of the pump tube meansand to be discharged from the outlet end, the water passing through thebasket and into the carafe positioned below the basket.
 2. An apparatusfor heating water therein by the application of microwave energy and fordispensing the heated water, comprising:a reservoir for receiving waterto be heated, the reservoir defining a closed chamber and a fillingaperture for introducing water into the chamber; conduit means having aninlet end and an outlet end, the inlet end extending into the reservoirto a position adjacent the bottom surface of the chamber, the conduitmeans being removably attached to the reservoir, the attachment of theconduit means to the filling aperture sealing the chamber from ambientair pressure, the reservoir being substantially transparent to microwaveenergy such that, upon exposure of the apparatus to microwave energy,water in the closed, sealed chamber is heated, increasing overtime thevapor pressure within the reservoir, the pressure increase forcing waterthrough the inlet end of the conduit means to be discharged from theoutlet end of the conduit means.
 3. An apparatus as claimed in claim 2wherein the conduit means defines an inverted, substantially U-shapedpassageway.
 4. An apparatus as claimed in claim 3 wherein the outlet endof the conduit means is vertically above the inlet end of the U-shapedpassageway.
 5. A microwave brewing apparatus for use within a microwaveoven for brewing a heated beverage by contacting a brewing material withwater heated by application of microwave energy, the apparatuscomprising: reservoir means defining a chamber for retaining a quantityof water to be heated, a carafe adapted to receive a quantity of brewedbeverage, pump tube means having an inlet end extending into thereservoir means to a position adjacent the bottom of the chamber and anoutlet end, retaining means for retaining a quantity of brewingmaterial, the retaining means positioned below the outlet end of thepump tube means and above the carafe, and means for sealing the chamberdefined by the reservoir means from ambient air pressure, whereby waterwithin the chamber is heated by application of microwave energy isforced from the reservoir into the inlet end of the pump tube means andis discharged from the outlet end of the pump tube means into theretaining means by an increase in vapor pressure within the chambercreated by the heating of the water by the microwave energy, theretaining means adapted to receive the heated water from the outlet endand direct the heated water into contact with brewing material thereinand brewing a beverage therefrom, the retaining means further adapted todischarge brewed beverage into the carafe while retaining the brewingmaterial therein.
 6. A microwave brewing apparatus as claimed in claim 5wherein the pump tube means is removably attached to the reservoirmeans.
 7. A microwave brewing apparatus as claimed in claim 5 whereinthe brewing material is tea.
 8. A microwave brewing apparatus as claimedin claim 7 wherein the tea is retained in a tea bag.
 9. A method ofmaking a beverage in a microwave oven, which employs an apparatus havinga microwave transparent pressurizable liquid reservoir disposed above afilter basket adapted to hold a quantity of brewing material, thereservoir and the filter basket adapted to be placed over a beveragereceiving carafe, the reservoir being in fluid communication with thefilter basket through a pressure overflow transfer means, the methodcomprising:pouring a liquid into the liquid reservoir to a level notexceeding the overflow level of the transfer means; placing a supply ofbrewing material in the filter basket; positioning the reservoir oversaid filter basket and placing the reservoir and the filter basket overthe carafe; closing the reservoir; heating the liquid in the reservoirwith microwave energy to raise the liquid vapor pressure in thereservoir sufficiently to force the liquid from the reservoir throughthe pressure overflow transfer means and into the filter basket to makea beverage; and collecting the beverage in the carafe.
 10. The method ofclaim 9 wherein the liquid is water.
 11. A beverage brewing apparatusfor use in a microwave oven, adapted to be placed over a beveragereceiving carafe having an open end, comprising:a filter basket adaptedfor holding a quantity of brewing material and for dispensing a brewedbeverage therefrom into the carafe; a pressurizable microwavetransparent reservoir adapted to hold a quantity of liquid up to apredetermined level, the reservoir positioned generally above the filterbasket; and pressure overflow transfer means through which the reservoiris in fluid communication with the filter basket and which is adapted tohold the liquid within the reservoir until the pressure in the reservoirrises sufficiently to force the liquid at least partially through theoverflow means into the filter basket.
 12. The apparatus as claimed inclaim 11 wherein the pressure overflow transfer means comprises anoverflow conduit which connects the reservoir with the filter basket,the upper end of the overflow passageway being disposed above thepredetermined liquid level in the reservoir, and an inlet passagewayhaving an open lower end extending adjacent the bottom of the reservoir.13. The apparatus as claimed in claim 11 wherein the liquid is water.